A signal processing apparatus that digitally processes a video signal (for example, a signal processing apparatus used for a digital VTR (Video Tape Recorder) that records/reproduces a high resolution video signal) compresses and encodes an input video signal. The compressed and encoded video signal is recorded to for example a video tape. To record/reproduce record data at a high data rate, a helical scan type recording/reproducing apparatus of which a magnetic tape is diagonally wound around a rotating drum and magnetic heads are disposed on the rotating drum is known. This apparatus successively records data in such a manner that diagonal tracks are formed on the magnetic tape.
When record data composed of a digital video signal and so forth is recorded on a tape, auxiliary data necessary for recording/reproducing data is also recorded. The record data is normally delimited in each data unit. In the following description, the data unit is referred to as sync block. The auxiliary data is position information on the tape (for example, time code) and information necessary for recording/reproducing process. The auxiliary data is structured as sync block and recorded on the tape. Many sync blocks are recorded on one track. One of sync blocks recorded on each track is assigned to auxiliary data. A sync block composed of auxiliary data is referred to as auxiliary data sync block.
In the conventional digital VTR, an auxiliary data sync block is recorded at the same position of each track. Thus, when a tape is scratched in the traveling direction thereof (namely, in the longitudinal direction), a situation of which auxiliary data cannot be reproduced at all sometimes takes place. Such a recording method is suitable for recording data such as a time code, for example, that is what the same contents are redundantly recorded on another track (longitudinal track). However, that method is not suitable for recording an auxiliary data that is necessary information for the reproducing process, because the reliability is very low.